Free Valence Electron Centralization Strategy for Preparing Ultrastable Nanoclusters and Their Catalytic Application.

Metal nanoclusters have attracted extensive interests owing to their atomically precise structures as well as intriguing properties. However, silver nanoclusters are not as stable as their gold counterparts, impeding the practical applications of Ag nanoclusters. In this work, a strategy of free valence electron centralization was exploited to render parent Ag nanoclusters highly stable.

Density Functional Theory Investigations on the Mechanism of Formation of Pa(V) Ion in Hydrous Solutions.

Due to the enormous threat of protactinium to the environment and human health, its disposal and chemistry have long been important topics in nuclear science. [PaO(H₂O)₆] is proposed as the predominant species in hydrous and acidic solutions, but little is known about its formation mechanism. In this study, density functional theory (DFT) calculations demonstrate a water coordination-proton transfer-water dissociation mechanism for the formation of PaO in hydrous solutions.

Atomically Precise Noble Metal Nanoclusters as Efficient Catalysts: A Bridge between Structure and Properties.

Improving the knowledge of the relationship between structure and properties is fundamental in catalysis. Recently, researchers have developed a variety of well-controlled methods to synthesize (NCs). NCs have shown high catalytic activity and unique selectivity in many catalytic reactions, which are related to their ultrasmall size, abundant unsaturated active sites, and unique electronic structure different from that of traditional nanoparticles (NPs).

Large-Scale Synthesis, Crystal Structure, and Optical Properties of the AgBr(SR) Nanocluster.

Solving the atomic structure of large-sized metal nanoclusters is a highly challenging task yet critically important for understanding the properties and developing applications. Herein, we report a stable silver nanocluster-AgBr(SR) (where SR = 4-isopropylbenzenethiolate)-with its structure solved by X-ray crystallography. Gram-scale synthesis with high yield has been achieved by a one-pot reaction, which offers opportunities for functionalization and applications.

Au(SR): the captain of the great nanocluster ship.

Noble metal nanoclusters are in the intermediate state between discrete atoms and plasmonic nanoparticles and are of significance due to their atomically accurate structures, intriguing properties, and great potential for applications in various fields. In addition, the size-dependent properties of nanoclusters construct a platform for thoroughly researching the structure (composition)-property correlations, which is favorable for obtaining novel nanomaterials with enhanced physicochemical properties. Thus far, more than 100 species of nanoclusters (mono-metallic Au or Ag nanoclusters, and bi- or tri-metallic alloy nanoclusters) with crystal structures have been reported.

X-ray crystal structure and doping mechanism of bimetallic nanocluster AuCu(m-MBT) (x = 1-3).

A novel AuCu(m-MBT) (x = 1-3, m-MBT = 3-methylbenzenethiolate) nanocluster has been prepared. According to the X-ray single crystal diffractometer, the structure of AuCu(m-MBT) is similar to that of Au(SPhBu). The AuCu(m-MBT) nanocluster contains a face-centered cubic (FCC) M core, which is protected by 4 MS (M = Au/Cu) staple motifs and 12 bridging SR ligands.

De-assembly of assembled PtAg units: tailoring the photoluminescence of atomically precise nanoclusters.

Considering the significant effect of the size of a nanocluster on its optical energy gap, we herein exploit the concept of de-assembly to render a blue-shift of the photoluminescent emission as well as an enhancement of the quantum yield (QY) of assembled M nanoclusters. The de-assembly splits an assembled M-dimer PtAg(PPh)Cl into a sole-M-kernel PtAg(dppm)(SPhMe), via a PtAg(SPhMe) nanocluster.

Multi-ligand-directed synthesis of chiral silver nanoclusters.

Engineering the surface ligands of metal nanoclusters is critical for tuning their sizes, structures and properties at the atomic level. Herein, we report the synthesis and total structure determination of [Ag(Dppm)(SAdm)Cl] and [Ag(Dppm)(S-Bu)Br] (where Dppm = bis(diphenyphosphino)methane, HSAdm = 1-adamantanethiol and HS-Bu = tert-butyl mercaptan). The compositions of these two silver nanoclusters are determined by single-crystal X-ray diffraction (SC-XRD) and X-ray photoelectron spectroscopy (XPS), respectively.

Shuttling single metal atom into and out of a metal nanoparticle.

It has long been a challenge to dope metal nanoparticles with a specific number of heterometal atoms at specific positions. This becomes even more challenging if the heterometal belongs to the same group as the host metal because of the high tendency of forming a distribution of alloy nanoparticles with different numbers of dopants due to the similarities of metals in outmost electron configuration. Herein we report a new strategy for shuttling a single Ag or Cu atom into a centrally hollow, rod-shaped Au nanoparticle, forming AgAu and CuAu nanoparticles in a highly controllable manner.

Thiol-Induced Synthesis of Phosphine-Protected Gold Nanoclusters with Atomic Precision and Controlling the Structure by Ligand/Metal Engineering.

Efficient synthesis of atomically precise phosphine-capped gold nanocluster (with >10 metal atoms) is important to deeply understand the relationship between structure and properties. Herein, we successfully utilize the thiol-induced synthesis method and obtain three atomically precise phosphine-protected gold nanoclusters. Single-crystal X-ray structural analysis reveals that the nanoclusters are formulated as [Au(Dppm)](BPh), [Au(Dppm)Br](BPh), and [Au(Dppm)(CN)] (where Dppm stands for bis(diphenylphosphino)methane), which are further confirmed by electrospray ionization mass spectrometry, thermogravimetric analysis, and X-ray photoelectron spectroscopy.

Mechanistic Investigation of Visible-Light-Induced Intermolecular [2 + 2] Photocycloaddition Catalyzed with Chiral Thioxanthone.

The recent thioxanthone-sensitizer-catalyzed intermolecular [2 + 2] cycloaddition induced by visible-light irradiation set the stage for the future development of feasible photocycloadditions. Nonetheless, the mechanism of this reaction still remains under debate, especially on the activation mode of the thioxanthone photosensitizer (energy transfer, bielectron exchange, and hydrogen transfer are all possible mechanisms). To settle this issue, systematic density functional theory calculations have been carried out.

The tetrahedral structure and luminescence properties of Bi-metallic PtAg(SR)(PPh) nanocluster.

The atomic-structure characterization of alloy nanoclusters (NCs) remains challenging but is crucial in order to understand the synergism and develop new applications based upon the distinct properties of alloy NCs. Herein, we report the synthesis and X-ray crystal structure of the PtAg(S-Adm)(PPh) nanocluster with a tetrahedral shape. PtAg was synthesized by reacting PtAg(SPhMe) simultaneously with Adm-SH (1-adamantanethiol) and PPh ligands.

In Situ Two-Phase Ligand Exchange: A New Method for the Synthesis of Alloy Nanoclusters with Precise Atomic Structures.

A new method termed "in situ two-phase ligand exchange" was developed to obtain alloy nanoclusters. With this approach, a series of alloy nanoclusters were obtained for the first time, including AuAg(SR), AuAg(SR) (x = 4-8), AuCu(SR) (x = 0, 1), and AuCu(SR) (x = 2-5) (R = tert-butyl). Interestingly, single-crystal X-ray crystallography (SC-XRD) shows that their frameworks are all alike except for AuCu(SR) (x = 2-5), indicating that more Cu dopants alter the structure.

Substrate-Assisted, Transition-Metal-Free Diboration of Alkynamides with Mixed Diboron: Regio- and Stereoselective Access to trans-1,2-Vinyldiboronates.

A substrate-assisted diboration of alkynamides using the unsymmetrical pinacolato-1,8-diaminonaphthalenato diboron (pinBBdan) is described. The transition-metal-free reaction proceeds in a regio- and stereoselective fashion to exclusively afford trans-vinyldiboronates in good to excellent yields. Notably, Bdan and Bpin are installed on the α- and β-carbon atoms, respectively.

Oxidation-Induced Transformation of Eight-Electron Gold Nanoclusters: [Au(SR)] to [Au(SR)].

Here we report an oxidation-induced transformation of [Au(S-c-CH)]TOA (S-c-CH: cyclohexanethiolate; TOA: tetraoctylammonium) to the [Au(S-c-CH)] nanocluster by HO treatment under ambient conditions. This is the first example of oxidation-induced transformation of one stable size to another with atomic precision. The product was crystallized and analyzed by X-ray crystallography.

Crystal Structures of Two New Gold-Copper Bimetallic Nanoclusters: CuAu(PPh)(PhCHS)Cl and CuAu(PPh)(BuPhCHS)S.

Herein, we report the synthesis and atomic structures of the cluster-assembled CuAu(PPh)(PhCHCHS)Cl and CuAu(PPh)(BuPhCHS)S nanoclusters (NCs). The atomic structures of both NCs were precisely determined by single-crystal X-ray crystallography. The CuAu(PPh)(PhCHS)Cl NC was assembled by two icosahedral M via a vertex-sharing mode.

Ag(Dppm)(SR) and Its Homologue AuAg(Dppm)(SR) Alloy Nanocluster: Seeded Growth, Structure Determination, and Differences in Properties.

A large thiolate/phosphine coprotected Ag(Dppm)(SR) nanocluster was synthesized through the further growth of Ag(SR) nanocluster and characterized by X-ray photoelectron spectroscopy (XPS), electrospray ionization mass spectrometry (ESI-MS), and single-crystal X-ray analysis. This new nanocluster comprised a 32-metal-atom dodecahedral kernel and two symmetrical Ag(SR)P ring motifs. The 20 valence electrons correspond to shell closure in the Jellium model.

Evolution from the plasmon to exciton state in ligand-protected atomically precise gold nanoparticles.

The evolution from the metallic (or plasmonic) to molecular state in metal nanoparticles constitutes a central question in nanoscience research because of its importance in revealing the origin of metallic bonding and offering fundamental insights into the birth of surface plasmon resonance. Previous research has not been able to probe the transition due to the unavailability of atomically precise nanoparticles in the 1-3 nm size regime. Herein, we investigate the transition by performing ultrafast spectroscopic studies on atomically precise thiolate-protected Au, Au, Au, Au, Au and Au nanoparticles.

The coordination of amidoxime ligands with uranyl in the gas phase: a mass spectrometry and DFT study.

Sequestering uranium from the ocean is a promising solution to fulfill the demand for nuclear energy. Motivated by this purpose, a series of amidoxime ligands and their analogs have been developed with high absorption capacity and selectivity. An in-depth understanding of the structural information of the uranyl-ligand complexes is essential to improve the performance of the ligands.

Total Structure Determination of Au21(S-Adm)15 and Geometrical/Electronic Structure Evolution of Thiolated Gold Nanoclusters.

The larger size gold nanoparticles typically adopt a face-centered cubic (fcc) atomic packing, while in the ultrasmall nanoclusters the packing styles of Au atoms are diverse, including fcc, hexagonal close packing (hcp), and body-centered cubic (bcc), depending on the ligand protection. The possible conversion between these packing structures is largely unknown. Herein, we report the growth of a new Au21(S-Adm)15 nanocluster (S-Adm = adamantanethiolate) from Au18(SR)14 (SR = cyclohexylthiol), with the total structure determined by X-ray crystallography.

The solely motif-doped Au36-xAgx(SPh-tBu)24 (x = 1-8) nanoclusters: X-ray crystal structure and optical properties.

We report the observation of new doping behavior in Au36-xAgx(SR)24 nanoclusters (NCs) with x = 1 to 8. The atomic arrangements of Au and Ag atoms are determined by X-ray crystallography. The new gold-silver bimetallic NCs share the same framework as that of the homogold counterpart, i.

Mechanistic Study on Gold-Catalyzed Highly Selective Hydroamination of Alkylidenecyclopropanes.

Density functional theory calculations have been carried out to study the mechanism of the gold-catalyzed highly selective hydroamination of alkylidenecyclopropanes. Two main mechanisms (i.e.

Density functional theory investigation on Pd-catalyzed cross-coupling of azoles with aryl thioethers.

In the present study, a density functional theory (DFT) study has been carried out on the Pd-catalyzed coupling of azoles with aryl thioethers. Our effort is mainly put into identifying the most feasible catalytic cycle, and especially the origin of chemoselectivity for the exclusive aromatic Csp(2)-S bond activation (in the presence of an alkyl Csp(3)-S bond). The coupling mainly consists of three steps: C-S activation, NaO(t)Bu mediated C-H palladation, and reductive elimination.